64bit op 64bit -> 128bit, library(mul, div, divmod)
[a[1], a[0]] / b = return, 答えが64bitに収まらないとヤバイ
[a[1], a[0]] % b = return, 答えが64bitに収まらないとヤバイ
a * b = (return[1]<<64) + return[0]
See Source File
64bit op 64bit -> 128bit, library(mul, div, divmod)